Avalanche Forecast

Issued: Mar 29th, 2013 9:38AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Cornices, Loose Wet and Wind Slabs.

swerner, Avalanche Canada

South Rockies.

The region will be under the influence of a major warm-up through the weekend. Be aware of snow conditions changing quickly and avalanche danger increasing.

Summary

Confidence

Good

Weather Forecast

TheÂ region will be under a significant high pressure system and blocking pattern that won't allow any active weather throughout the forecast period. Sunny skies with few clouds and high freezing levels will continue.Saturday: Sunny with possible high cloud in the afternoon. Alpine temperatures near -1.0 and freezing levels rising to 2600 m. Ridgetop winds will blow light from the NW.Sunday: Sunny. Alpine temperatures 2.0 degrees and freezing levels 2700 m. Ridgetop winds will be light from the NW.Monday: Sunny. Alpine temperatures near 2.0 degrees and freezing levels hover around 2500 m. Ridgetop winds blowing light from the West.

Avalanche Summary

No new observations reported today.On Thursday, several loose wet avalanches size 1 initiated from steep Southerly terrain.Â

Snowpack Summary

Cornices are large and will likely become weak due to strong solar radiation and warming temperatures. The surface snow has become moist or wet up to 2200 m, especially on solar aspects. Melt-freeze conditions exist. Wind slabs exist in the immediate lee of ridge lines and terrain features. Surface hoar and surface facetting is forming on sheltered, northerly aspects, especially at higher elevations.Up to70 cm of settling snow sits on top of a buried rain crust down 50 cm and exists up to around 2100 m. The bond of this snow to the crust has shown variability though the region. It is important to dig down and test weak layers before dropping into your line. A large trigger such as a cornice fall or a skier/sledder hitting the sweet spot, could potentially trigger a large avalanche on this layer.

Problems

Cornices

Large looming cornices exist on most ridgelines. Cornices may become weak under the influence of the sun. They are a hazard in themselves and they could trigger slopes below.

Give cornices a wide berth when travelling on or below ridges.>Pay attention to overhead hazards like cornices.>

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 5

Loose Wet

Warmer afternoon temperatures and sunshine may promote deterioration within the upper snowpack. If surface snow becomes moist or wet, loose wet avalanches are likely. Watch solar aspects.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Watch for wet loose or slab activity with forecast warm temperatures.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: North, North East, East, South East, South.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Wind Slabs

Wind loaded and cross-loaded slopes can still be found at treeline and alpine elevations. A small wind slab avalanche could step down to the March 16th rain crust. Wind slabs may be triggered under the weight of a skier, rider or cornice fall.

Use extra caution on lee and cross-loaded terrain near ridge crests.>Whumpfing is direct evidence of a buried instability.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Mar 30th, 2013 2:00PM